Water tree retardation and electrical properties of EVA blendedXLPE

摘要

The water tree retardation effect of EVA (ethylene vinyl acetate)nblended XLPE (cross-linked polyethylene) was investigated. In additionnto water tree tests such electrical properties as dissipation factor andnAC breakdown strength and such mechanical properties as Young's modulusnand toughness were also studied, because the performance of insulatingnmaterials cannot be estimated only on the basis of water treenretardation. It is shown that, in the case of XLPE blended with EVA,nwater treeing can be retarded considerably and toughness correspondingnto the stress-crack resistance improved with increasing VA content,nwhile the dissipation factor which depends on the concentration ofnpermanent dipoles increases. No marked change of AC breakdown strengthnwith increasing the VA content was observed. It is concluded that thengrowth of water tree is strongly influenced by the mechanicalnproperties, and improvement of stress-crack resistance may be a possiblenway to reduce water treeing